It doesn't "mean" that. It "could" mean that but it isn't definitely the case. Missing checkdowns means exactly that. There is no qualifier about him looking deep or trying to make plays.
For whatever reason he didn't go with the primary option(s) but still missed the checkdowns. That has long been the problem with Goff. Ever since the '18 CHI game as a matter of fact. McVay and his scheme are providing positive plays to be had but Goff is not taking them and/or not seeing them. I have long felt that his overnight success and gaudy numbers ultimately retarded his growth. And I still feel that his learning curve didn't truly start until after the bye in '18.
It is said that most QB's take 3 years for the game to truly slow down for them and, assuming the prorated scale theory I have, that 3 year mark is still coming. Best case scenario is that this year has been the darkness before the dawn and that next year Goff reaches that comfort level. Well, starting this Saturday hopefully.